Thanks Young Spade. I will be doing videos up to 8 minutes in full HD with 3D modelling (as in moving the camera's perspective and looking from behind). If I am just running one instance of AfterEffects CS5.5, will I really notice a significantly smaller time in the rendering of a video?
Well what you have to think about is the speed at which you see the renders in real time, when you're playing the video back, not the actual rendering of the file (I'm not sure whether you're talking about the former or latter).
What I'm saying is, like, with a MBP, the GPU is the bottleneck when doing actual editing on it (seeing the renders when you're shuffling through the timeline) but it renders the final video file with ease.
Now with that said, I suggest (if you haven't done so already), try looking for youtube videos with the computer that you want to get (or other imacs of lower configuration) and try to watch people edit their videos using the same program or whatever.
That will give you an idea of how well each graphics card holds up.
The SNB processor is going to handle the rendering just fine, but you're obviously thinking logically about whether to get the 1 or 2 without just throwing the money away, so that's always good.
You can just splurge and get the 2 if you have the money, as it isn't something you can upgrade later. If you're doing this for a job or it's really serious to you, I'd say to just get the 2. Down the road, you might start working on more intense projects and you won't be able to take the card out and put a better one in later (or can you?)
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Who would pay $200 for 2GB of RAM? I don't care who you are, how much money you have, or what kind of projects you are working on - the answer is NO. Take your $200 and give it to a homeless shelter you will get more use out of it.
Now to troll - go build yourself a PC and you'll have a better product and can give yourself a 2GB RAM upgrade for $20.
It's graphics card RAM, not standard RAM. Now yea, you're paying a lot more for that card, but it isn't dirt cheap like the 8 gigs for 50 you can find online.